Final answer:
Intervertebral discs consist of the anulus fibrosus and the nucleus pulposus; the former is the tough exterior layer, while the latter is a gel-like core that helps absorb compression.
Step-by-step explanation:
The intervertebral discs, which cushion and separate the vertebrae in the spine, consist of two major components: the anulus fibrosus and the nucleus pulposus. The anulus fibrosus is a tough, fibrous outer layer that encircles the disc and is connected to the adjacent vertebral bodies. Within this protective ring lies a softer, gelatinous core known as the nucleus pulposus, which maintains high water content to help resist compression and sustain weight bearing.
As individuals age, the water content in the nucleus pulposus diminishes, leading to a reduction in disc thickness and height. Consequently, this decreases the spine's flexibility and motion range, often making bending more difficult and increasing the potential for disc herniation if the anulus fibrosus is damaged.